Agree with others about in-state options. UDel has a well respected program in both math and CS. Start your list there - the instate tuition is reasonable. Every year, our local high school in NJ sends a contingent of kids to UDel, paying OOS tuition to help support the beautiful campus. Only heard good things about the school.
For math and CS, pretty much every flagship in the NE area is pretty strong. Aside from the campus differences, the programs themselves are pretty similar.